Field-induced single-ion magnet behaviour of a hexacoordinated Co(ii) complex with easy-axis-type magnetic anisotropy

Abstract

This study presents the novel hexacoordinated Co(ii) mononuclear complex with SIM behavior.

Field-induced single-ion magnet based on a quasi-octahedral Co(ii) complex with mixed sulfur–oxygen coordination environment

“…The energies for the low-lying spin-free (δ E ) and spin-orbit (Δ E ) states, those being the energies of the terms and Kramers doublets, respectively, are given in Table 1. The six lowest in energy spinorbit states (Kramers doublets) roughly correspond to the Griffith diagram [8] at a large positive value of the axial crystal field parameter; also, the first quartet excited state is well separated from the ground one (Table 1), thus showing that the used spin-Hamiltonian description is an adequate one [29]. As can be observed, the d-orbitals splitting does not match D 4h distorted octahedral coordination; there is a strong destabilization of d z2 -orbital which is more characteristic for square planar coordination.…”

Fine-Tuning of Uniaxial Anisotropy and Slow Relaxation of Magnetization in the Hexacoordinate Co(II) Complexes with Acidoligands

“…2,2′-((Butane-2,3-diylidene)-bis­(hydrazin-1-yl-2-ylidene))­bis­(4,6-dimethylpyrimidine) ( L ) was synthesized, as described earlier . All other reagents and solvents were purchased from commercial sources and used without further purification.…”

“…Here, we report the structure, magnetic properties, and ab initio quantum-chemical study of compound 1 in comparison with the previously reported compound 2 differing from 1 by the apical monodentate ligands.…”

“…On the other hand, D S is determined by the local (single-ion) anisotropy parameters D i and hence the increase of single-ion anisotropy can be regarded as the most suitable strategy for the increase of U eff . This allows even mononuclear complexes behaving as SMMs (i.e., SIMs) to be obtained, provided that the single-ion anisotropy is high enough. − For this reason, the control of axial magnetic anisotropy is under thorough research interest in the field of molecular magnetism. ,, Magnetic anisotropy of mononuclear compounds is the property influenced by multiple factors such as nature of the metal ion, shape of the coordination polyhedron, ligand-field (LF) strength, spin–orbit coupling (SOC), spin–spin coupling, and so forth, thus making design, control, and fine-tuning of magnetic anisotropy a really challenging goal. ,,− Among 3d ions, the most promising candidates for SIMs are coordination compounds of the high-spin Co­(II) ions with d 7 electronic configuration. , Though the largest value of U eff has been so far achieved for highly unstable low coordinate Co­(II) complexes, ,, it was shown that much more chemically stable hepta- ,− and hexacoordinate − compounds are still promising for building up magnetic anisotropy of Co­(II)-based SIMs by means of a proper ligand design. One of the strategies of fine-tuning magnetic anisotropy is to isolate the LF influence on the d-type atomic orbitals (d-AOs) of a certain symmetry to have the possibility to adjust d-AO’s energy and splitting pattern.…”

A Series of Field-Induced Single-Ion Magnets Based on the Seven-Coordinate Co(II) Complexes with the Pentadentate (N3O2) H2dapsc Ligand

“…One of the approaches to increase magnetic anisotropy is to use special ligands with a less-common coordination since the anisotropy depends on the coordination number of the metal centers [5,6]. The magnetic anisotropy can be improved by a rational ligand design [7][8][9][10][11][12][13][14][15]. The "ligand approach" has already led to a variety of mononuclear 3d metal ion-based SMMs (so-called single-ion magnets (SIMs)) with improved characteristics [6].…”